Preparation of Remote NHC Complexes of Rhodium(I) and Gold(I) by Ligand Transfer

The rNHC complexes (5‐butyl‐1,2‐dimethylpyridin‐4(1H)‐ylidene)Cr(CO)5 (1), as well as the novel compounds (1,2‐dimethyl‐5‐phenylpyridin‐4(1H)‐ylidene)M(CO)5 (2, M = Cr; 3, M = W) and (1‐methylpyridin‐4(1H)‐ylidene)Cr(CO)5 (7) were prepared from Fischer carbene complexes. Reaction of 1 with [Rh2(μ‐Cl)2(CO)4] then afforded the first rNHC RhI complex, 4. Transfer of the ligand in 2 to Ph3PAu+ afforded the cationic rNHC gold complex, 5 and reaction of 3 and 7 with [AuCl(tht)] gave the neutral rNHC–AuCl complexes 6 and 8. The compounds were characterised by IR and multinuclear NMR spectroscopy as well as mass spectrometry. The crystal and molecular structures of the remote pyridinylidene complexes 3, 4, 5, 6 and 8 were determined by single‐crystal X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)